1. Field of the Invention
The present invention relates to a sheet processing apparatus that processes a sheet and an image forming apparatus having the same.
2. Description of the Related Art
A sheet processing apparatus disclosed in U.S. Patent Application Publication No. 2007/051219 A1 includes an attitude correcting portion that corrects print skew and aligns a leading edge of a sheet by allowing the leading edge to bump against something and a punching portion having a punch that performs a punching process on the sheet. The sheet processing apparatus further includes a lateral registration adjustment portion which can adjust the position of the punch of the punching portion in relation to the sheet of which the attitude is corrected by the attitude correcting portion in a direction vertical to a moving direction of the sheet before the punching portion performs the punching process.
A sheet processing apparatus having such a configuration that a punching portion is detachably attached to a fixed support having a driving source of the lateral registration adjustment portion and the type of the punching portion can be recognized when the punching portion is attached. Due to this, the sheet processing apparatus can be easily replaced according to punching conditions such as a punch hole and the number of holes and can automatically recognize set conditions and alignment during replacement.
In a sheet processing apparatus in which a punching portion can be replaced, the punching portion may be replaced with a scoring portion to cut lines in a sheet or may be replaced with a perforating portion to make perforations.
However, since it is necessary to press a convex and concave mold with uniform force in a sheet width direction in order to cut lines uniformly in the sheet, large processing force is required as compared to punching which can decrease processing force by punching with a time difference.
Due to this, since it is necessary to decrease a rotating velocity of a motor which is a driving source to increase torque, the processing time increases. As a result, productivity decreases. The same problem occurs in the perforating portion since the perforating portion performs processing in the entire sheet width direction.
The present invention has been made in view of the problem and it is desirable to provide a sheet processing apparatus of which the productivity is not impaired by a sheet processing portion.